Into The Cement Mixer: Dirt, Diapers and the Future of Construction

May 15, 2015

     The ground shakes a few hundred feet away when the 20-ton slab of concrete hits the earth. Wespac Construction Inc. of Phoenix, Arizona is leading the way for a greener community by incorporating the process of deep dynamic compaction (DDC) on projects across the valley. In a city where quality real estate is becoming more difficult to come by, transforming forgotten pieces of land through such innovative processes is beneficial to businesses, communities and the environment alike.

     The process of improving the site foundation is fairly simple: a concrete drop-weight is used to densify soils and fills below. Depending on the weight and height from which it’s being dropped, the amount of stress waves can be altered in order to densify the soil appropriately. Moisture from waste materials and air pockets after layering can be released from the soil depending on the strength of the stress waves. Seemingly unsalvageable pieces of land, dump sites to be exact, can be transformed from piles of waste to considerable pieces of land. Real estate prices are critical factors for developers when choosing between high priced properties and the countless dump sites all throughout greater metropolitan Phoenix. Dumps sites can be bought and transformed into better pieces of land for merely a fraction of the price of a standard piece of property. An estimated value of a dumpsite is in the range of $1-2 per square foot, and can be flipped as a working piece of property for as much as eight to ten times as much depending on the location.

     It may seem appealing to developers, but problems are susceptible to arise if contractors don't take precautionary measures. Depending on the material the dump site contains, either organic or inorganic, contractors choose their next steps in order to overcome potential obstacles. Inorganic sites such as I-10 Airpark or Liberty Center saw different preparations than organic sites. Concrete waste and metal scraps can simply be crushed by the compounded earth, becoming uniformly dense at a much faster rate and shaving off valuable building time in the process.

     An organic dump site such as Tempe Business Park is prone to a longer compaction process depending on the amount of waste material, swelling, and differential settlement. The amount of moisture absorbing into the settling earth plays an enormous role in order to achieve the necessary psi(pounds per sq. inch) required to start building. Sites such as Tempe Business Park and Liberty Center call for longer preparation time than most sites considering the proximity to Tempe Town Lake. On sites so close to flowing water that also contains organic materials like trash, preparation is a much more strenuous and time consuming in order to ensure the required psi. Potential complications like liquefaction, differential settlement, and swelling from moisture are the biggest factors when observing serious risks for organic dumpsites on the banks of flowing water.

     "A site like I-10 or Liberty Center takes somewhere in the range of months; I-10 was a little over ten months, and Liberty was only a few months to get the required psi. However, an organic site like Tempe Business Park may take a year of pounding, maybe even more," Wayne Bogan, Principal of Wespac Construction and overseer of I-10 Airpark said. “Risks are always higher on sites with organic materials like trash, but flowing water and moisture below the landfill create additional risks to an already tricky feat.”

     Results from a successful reclamation can be astonishing when looking at the numbers. The psi of a normal piece of real estate may be in the range of 2,500-2,700 for a nice piece of property, whose bill runs a great deal higher than a dump. "The psi reached at I-10 Airpark was 3,000," Wayne commented.

    Although air pockets and moisture add risks and preparation time for sites such as Tempe Business Park, the rewards in developing cheap land speak in both financial and collective terms. The countless dump sites throughout the greater Phoenix area, both organic and inorganic, are proving to be the future sites for more green development. With tenants already occupying I-10 Airpark and Liberty Center, the numbers are beginning to speak for themselves. This green process and outward thinking for the future gives reasoning for Wespac  President and founder, John Largay, to comment on the technique, "it is turning diapers into dollars."

Category: Projects